The basis of numbers based on dozens, like 360 (degrees), is because for many centuries, engineers did not have algorithms for division.
The way you do divisions was popularized by Al-Juarizmi (in spanish, or al-Khwārizmī in imperial units), based on the system devised by Indian mathematicians (let's bless them!). He introduced people to zero and arabic numbers. Since then, dividing is easy.
However, before Mr. Juarizmi, can you imagine how hard was to divide CCXXV by XVI?
So, when you use a number like 360 as a "base" you can divide it by 1 (good joke!), 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 24, 30, 36, 40, 45, 60, 72, 90 and 180 and you get an integer.
Same goes with 12: it's divisible by 1 (ha, ha), 2, 3, 4, 6, 8 ("almost" an integer: 1.5) and 9 (almost integer, again: 1 1/3). By "almost" I mean you can "divide in your head".
No people with 6 fingers was involved in the system that "tries" to use numbers based on multiples of 12, except, perhaps, some viking navigators and their strayed dogs (ha, ha, how funny I am!).
The idea of using 16, like in 1/16 of an inch, is not equally good: you cannot do an integer division by 3 or 5. I think that the "most divisible" (integer results, of course) number in the first few hundreds is 360, but I'm not sure. In the first twenty numbers, 12 is the king of integer division, of course.
Anyway, as I'm not a mod anymore (altough by some mistake I still have the rights) I have to ask nicely
and rudely (phew, at last, free at last!):
any possibility of staying on thread, instead of writing this mountain of stupid posts? You, mates, are missed elsewhere.
Of course, this thread is hopelessly uninteresting: why would someone use imperial units? Let me guess: because his nation is not interested in exports, only in accumulating debt (even in you live in Burma or Liberia, two of the three nations that obstinately, hardheadedly and bordering imbecility, still use the imperial system). I apologize to any Burmese or Liberian in the forum: it's your government the one at fault, not your nation.
For Just a fan: there is such thing as a metric adjustable spanner (aka adjustable wrench: we don't communicate in english, we comunicate, if we do so, in international english, which means we talk as we can). Anyway, dear JAF, check what a milli-grip is.
Finally,
there is no such thing as a metric system in use nowadays: the metric system was overrode by the Système internationale d'unités (SI).
This happened in 1960, engineers. Don't you, people, read? It's very useful to do so.
So:
http://www.physics.ohio-state.edu/~joss ... t-A4-1.pdf
Read the first article, by Mr. Petley, if you want to get a grip of why SI and how it will evolve.
In his own words: "During its nearly forty years of use, the SI has been modified as science and technology have advanced. To the great satisfaction of most physicists,
the artefact standards are being replaced by units and standards that are based on atomic and quantum phenomena. The process seems likely to continue for the next few decades, reflecting the fact that nature does not provide a unique set of natural units.
Please, don't bother answering this post: I'm going to deep freeze myself and I plan to wake up in 200 years.
), I'm reminded of a story (probably apocryphal) of apprentices being sent to the storeroom for an adjustable spanner. "And make sure you get an imperial one - none of that metric rubbish". Apparently anyone who didn't figure it out before they got to the storeroom was unlikely to be kept on the books for very long 
